The shooting of "Umizaru" is done with the full cooperation of the Japan Coast Guard, including the provision of vessels, helicopters, uniforms, and other props.
Although he became a rescue diver a year before, Daisuke Senzaki was frustrated from having no real life rescue experience. One day, he is transferred to the 3rd Region of the Japan Coast Guard in Yokohama. Daisuke is thrilled that he's able to work in the same city where his girlfriend Kanna lives. He is posted to the patrol vessel "Nagare." The captain is Kotaro Katsuta, the commander of rescue divers is Iwao Shimokawa, and Daisuke's "buddy" (diving partner) is Masaki Ikezawa, an elite rescue diver. Masaki is a professional who is strict both on himself and his colleagues, but he expects nothing from a novice like Daisuke and hardly even talks to him. One day, an oil tanker "The Asian Trip" capsizes and patrol vessel "Nagare" embarks on a rescue mission.